Automata are abstract mathematical models of machines that perform computations on an input by moving through a series of states or configurations. If the computation of an automaton reaches an accepting configuration it accepts that input.

At each stage of the computation, a transition function determines the next configuration on the basis of a finite portion of the present configuration.

Automata are nothing but simple abstract computers that are :

Used to recognize languages.

And closely related to formal language theory.

Formal languages are used for defining syntactically correct programs.

An automaton is represented by the 5-tuple , where:

Q is a set of states.

Σ is a finite set of symbols, that we will call the alphabet of the language the automaton accepts.

δ is the transition function

q0 is the start state, that is, the state in which the automaton is when no input has been processed yet, where q E Q.

F is a set of states of Q called accept states.